Quantum oscillations and high carrier mobility in the delafossite PdCoO$_2$

TL;DR

This study reports exceptionally high in-plane electrical conductivity and carrier mobility in PdCoO2, a delafossite oxide, with detailed measurements revealing unique temperature-dependent resistivity behavior and quantum oscillations.

Contribution

The paper provides the first detailed de Haas-van Alphen and resistivity data on PdCoO2, demonstrating its record-high conductivity and elucidating the origins of its high mobility and low scattering.

Findings

PdCoO2 has the lowest resistivity among oxides at 295 K.

Transport mean free path exceeds 20 micrometers below 10 K.

Resistivity shows activated temperature dependence, indicating phonon drag effects.

Abstract

We present de Haas-van Alphen and resistivity data on single crystals of the delafossite PdCoO2. At 295 K we measure an in-plane resistivity of 2.6 \mu{\Omega}-cm, making PdCoO2 the most conductive oxide known. The low-temperature in-plane resistivity has an activated rather than the usual T^5 temperature dependence, suggesting a gapping of effective scattering that is consistent with phonon drag. Below 10 K, the transport mean free path is 20 \mum, approximately 10^5 lattice spacings and an astoundingly high value for flux-grown crystals. We discuss the origin of these properties in light of our data.